Arrangements for storing and launching payloads, such as counter-measures, being designed to be mounted on vehicles, such as an aircraft of the aeroplane type, are previously known. According to the state of the art, such arrangements comprise an elongate body provided with at least one launch opening. Such arrangements are mounted with the longitudinal direction of the elongate body essentially coinciding with the flight direction of the aircraft. The counter-measures being connected to a firing control unit for feeding firing signals to the counter-measures. The counter-measures can consist of passive means, such as chaff foil, but can also consist of flares, for example IR flares, or other active measures.
One problem is that unfavourable acoustic phenomenon, such as extremely high air induced noise and vibration levels, are generated due to the openings of the compartments, after firing of the counter-measures. The relative wind, due to the speed of the vehicle, interacts with the open, remaining cartridges of the compartments in which the counter-measures have been accommodated. The open compartments can act as barrels which oscillate at its inherent frequency. The acoustic phenomenon could be localised by target-seeking missiles and may also cause damage on the equipment, such as electric components, due to strong vibrations created.
The longitudinal extension and the number of openings of the compartments in the elongated body can be rather large. The protective effect of previously known vortex generators arranged in front of the compartments decreases with increasing length of the openings of the compartments.
Another problem is that previously known sound absorbing means, in arrangements according to the state of the art, generates turbulent flows that are difficult to control and results in high energy losses. The previously known sound absorbing means also contributes to an increased extension of the design of the arrangement in the longitudinal extension of the vehicle.
Yet another problem with the arrangements according to the prior art is the sensitivity for influence of the air flow that is affected by the speed and position of the vehicle.
An example of a previously known arrangement described as a dispenser which is used for launching counter-measures and provided with compartments, is described in document WO-A1-0059782. An elongated body of the dispenser is provided with fixed means, described as a spoiler, in front of the compartments for acting on the air stream and for creating a low dynamic pressure across the compartment openings.
From document U.S. Pat. No. 4,696,442 it is known to provide the exterior surface of an aircraft with a pair of vortex generators arranged right in front of an inlet opening in order to increase the mass airflow into the inlet.